If you are looking to add photos to the Photo Widget on your league website
Classic Website Editor:
Go to the Website tab and click Manage
In the upper right hover over 'Add-ons' and click Photos
Create an Album or select an existing album
Press '+ Add Photos' and select the Photo you'd like to Upload
Website Builder:
Go to the Website tab and click Builder
Hover over Add-ons at the top and select Photos
Create an Album or Select an existing one
Click Add Photos in the upper right